12 volt Electrical Battery Problems. Where is all the power going?

[tgpt21]

My service battery bank consists of two 110 Ah lead acid batteries. They are a little over three years old. They are charged from an old LEAB smart-charger in port and two 100 watt solar panels. We also have a suitcase generator if we need a top up. We never use the engine to merely charge the batteries unless we are motoring out of port.

We run two fridges together they take 8 amps approximately. At the moment we are in Ancona Marina hence the need for lots of cool drinks. In the last couple of weeks we've just been motoring out into the bay to swim and SUP. The batteries are 100% full when we leave and we motor out so no loss of power during the journey (you'd think).The fly in the ointment is that the battery bank will not run the two fridges. We are out for six hours even running the full six hours that's 48 amps, one quarter of the battery capacity and four amps in from the solar panels minimum.

I have a NASA battery monitor and within an hour the batteries have fallen off a cliff from 100% to 60% in an hour ( I understand the limitations of this instrument but broadly speaking we can say there is a BIG power drop). I immediately condemned the batteries and removed them with intention of buying new today. However, I had a single 110 AH battery which I wired in as a temporary measure overnight. I also let the free standing fridge run on the "old" batteries and they have produced the required amperage so far.

As a test, I switched off the mains battery charger. Damn me the new battery dropped like a stone just like the old batteries.

Where are all those amps going?

 

[halcyon]

What charge does the monitor show going into the batteries from the mains charger ?

Brian

 

[tgpt21]

What charge does the monitor show going into the batteries from the mains charger ?

Brian

Good morning Brian,

Thanks for your reply.

The reading varies of course as the batteries charge. I am running both fridges at the moment off the single 110 Ah battery. Because the NASA meter has been set for the 2 X 110 Ah then I assume that there will be a false %age reading. At the moment it shows 8.3 amps. But something I have always found strange is that the LEAB mains chargers shows 22 amps. There has always been an inconsistency.

I ran the freestanding fridge (takes 3 to 4 amps) from 1800 last night on one of the 110 Ah batteries and there was not enough to power it by 0300. It was fully charged at 1800 showing 13.0 volts and even at one point whilst disconnected showing over 15 volts! Does this indicate a problem? Never heard of this high reading before.

 

[MikeCC]

My guess is something wrong with solar setup. Look at the volts/amps display with sun out and fridge running. If it doesn't look right, isolate or switch off everything except panel input and see what the BM1 shows as power going in.

If you're getting nothing, solar charge is probably not connected through BM shunt. If it's showing less than expected, check the solar kit.

 

[MikeCC]

Don't forget the amps reading on BM is a NET figure of input and output.

 

[halcyon]

Good morning Brian,

Thanks for your reply.

The reading varies of course as the batteries charge. I am running both fridges at the moment off the single 110 Ah battery. Because the NASA meter has been set for the 2 X 110 Ah then I assume that there will be a false %age reading. At the moment it shows 8.3 amps. But something I have always found strange is that the LEAB mains chargers shows 22 amps. There has always been an inconsistency.

I ran the freestanding fridge (takes 3 to 4 amps) from 1800 last night on one of the 110 Ah batteries and there was not enough to power it by 0300. It was fully charged at 1800 showing 13.0 volts and even at one point whilst disconnected showing over 15 volts! Does this indicate a problem? Never heard of this high reading before.

Sounds like surface charge problems.

What you need to do is find out some facts, what is engine charge and voltages, what is mains charge and voltages, what is solar panel and voltages, that is with fridges off. This will give you what is happening on charge, with no charge, check your power loading, that is each fridge, radio, lights. Now make a note of what is switched on, fridges etc, and check your charge levels and voltages again.

It may be that you are getting to low a charge voltage, thus a low capacity, then when charging you get a surface charge that gives you the look of a charged battery.

Do not try and assume, get facts.

Brian

 

[KellysEye]

>The reading varies of course as the batteries charge. I am running both fridges at the moment off the single 110 Ah battery.

That could be the problem I've never seen a boat with two fridges, long distance sailing you go on a great many.

 

[[70521]]

I just ignore the percentage power available on the NASA instrument, voltage and amps are the two figures that I am interested in.

 

[noelex]

The NASA battery monitor is in essence an Amp hour counting battery monitor ( it has some slightly smarter technology but this plays little roll in the display). Therefore if you have programmed in a battery size of 220 Ahr and the display has dropped from 100% to 60% SOC in one hour the meter has measured an average current draw of around 0.4x220= 88A (this is ignoring Peukert equation).

So the display should be showing a current draw of this order of magnitude.

If it does not. The most likely explanation is the programmed battery capacity is incorrect.

Is the programmed battery capacity incorrectly set to 22Ahrs rather than 220Ahrs?

 

[tgpt21]

Hi Mike,
Thank you for your reply.

I understand the net input/output idea. The solar panels are connected to the battery meter. Although I do plan to dive in and redo all the connections.

The second fridge is a Mobicool box type thing which is very good. It is connected to a 12 volt cigar lighter connection when we are at sea. I've just this moment noticed it is when the voltage reaches 12.6 that it cannot be driven off this connection. Yet I have connected it directly to the "old" recently removed and suspect 110 Ah battery it is working OK despite there only being 12.5 across the terminals connected.

 

[tgpt21]

Sounds like surface charge problems.

What you need to do is find out some facts, what is engine charge and voltages, what is mains charge and voltages, what is solar panel and voltages, that is with fridges off. This will give you what is happening on charge, with no charge, check your power loading, that is each fridge, radio, lights. Now make a note of what is switched on, fridges etc, and check your charge levels and voltages again.

It may be that you are getting to low a charge voltage, thus a low capacity, then when charging you get a surface charge that gives you the look of a charged battery.

Do not try and assume, get facts.

Brian

I have done all that not just since this problem. I routinely monitor the monitor and adjust the 3 way switch according to where the charge is needed. I have a separate ammeter on the solar controller which I check and take great delight in seeing this free energy. I have a separate voltmeter for the cranking battery. I do not assume anything other than if something can go wrong it will go wrong. I do base my actions on facts.
I am beginning to wonder if the mains charger is past its best and the batteries are not being fully charged. I do not know how I would test this.

 

[tgpt21]

The NASA battery monitor is in essence an Amp hour counting battery monitor ( it has some slightly smarter technology but this plays little roll in the display). Therefore if you have programmed in a battery size of 220 Ahr and the display has dropped from 100% to 60% SOC in one hour the meter has measured an average current draw of around 0.4x220= 88A (this is ignoring Peukert equation).

So the display should be showing a current draw of this order of magnitude.

If it does not. The most likely explanation is the programmed battery capacity is incorrect.

Is the programmed battery capacity incorrectly set to 22Ahrs rather than 220Ahrs?

Hi,

Thanks for your reply. I am sure that the the monitor has been programmed correctly. It has been in for years and has been operating ok until the last week.

Your point that if in an hour there is a 40% drop and it is not showing on the monitor is a valid one. The current cannot leave the batteries without going through the monitor. Am I correct in this posit. I would say assumption but I've been chastised for assuming already today. LOL

 

[tgpt21]

I just ignore the percentage power available on the NASA instrument, voltage and amps are the two figures that I am interested in.

Agreed but I'd never seen the % fall so fast! I have a Gib Sea 372. Are you as happy with your's as I am with mine?

 

[Poey50]

Whatever the specifics of the problem, that is an unusually high fridge to battery ratio.

 

[pvb]

Whatever the specifics of the problem, that is an unusually high fridge to battery ratio.

I'd agree, the battery bank is really too small for the loads.

 

[tgpt21]

Whatever the specifics of the problem, that is an unusually high fridge to battery ratio.

You're so correct. Actually the single battery that's in now was to add to the original two so that the ratio was 3:2. There is a story to how be have two fridges. The Mobicool was bought when the built in fridge went all wrong. I managed to bodge a repair on the built in number it only just keeps the food fresh in this heat. But in the Mobicool what luxury was found. It goes down to minus five so quickly. MINUS FIVE. It cools gin and vermouth so that the cocktail hour brims forth martinis that freeze the gums. Lager is cold enough to satisfy even Sir John Mills (showing my age there). We just refuse to do without it. More solar panels next year.

 

[tgpt21]

I'd agree, the battery bank is really too small for the loads.

You're so correct. Actually the single battery that's in now was to add to the original two so that the ratio was 3:2. There is a story to how be have two fridges. The Mobicool was bought when the built in fridge went all wrong. I managed to bodge a repair on the built in number it only just keeps the food fresh in this heat. But in the Mobicool what luxury was found. It goes down to minus five so quickly. MINUS FIVE. It cools gin and vermouth so that the cocktail hour brims forth martinis that freeze the gums. Lager is cold enough to satisfy even Sir John Mills (showing my age there). We just refuse to do without it. More solar panels next year.
Read more at http://www.ybw.com/forums/showthrea...all-the-power-going/page2#tgZFuE8QQogM1IkC.99

 

[duncan99210]

I’m in the same part of the world as the OP, with a single fridge which pulls about 6 amps when running, which it does for about 50% of the time (hot out here) so say 72 amp hours per day. I have 260 watts of solar power, which puts about 6 amps or so back into the batteries for about 10 hours a day, say 60 amp hours. Thus, I’m always playing catch up until we move the boat, when we reckon on paying back the power overdraft.
The domestic bank is 500 amp hours of sealed batteries.
In addition, the OP is using a Mobicool box, which is thermoelectric cooler rather than a compressor fridge as his second fridge. They’re always on, unlike a compressor fridge which cycles on and off using a thermostat, and have a reputation for using a lot of power for not a lot of cooling.
So what? In the Ancona area, the temperature is such that the fridges will be working hard. So the battery bank needs to be large enough to cope with the load. The OP has a compressor fridge, so say 72 amp hours a day, plus the Mobicool at say 96 amp hours a day: that’s way too much for his 220 amp hour bank to sustain, even if he’s going into the marina every night and using shore power. The current batteries are knackered, not holding their charge which is why he’s seeing the battery monitor drop so quickly. Solution is to replace the batteries, add at least another 220 amp hours worth of batteries to the bank OR stop using the Mobicool box ( but still replace the batteries).

 

[tgpt21]

I’m in the same part of the world as the OP, with a single fridge which pulls about 6 amps when running, which it does for about 50% of the time (hot out here) so say 72 amp hours per day. I have 260 watts of solar power, which puts about 6 amps or so back into the batteries for about 10 hours a day, say 60 amp hours. Thus, I’m always playing catch up until we move the boat, when we reckon on paying back the power overdraft.
The domestic bank is 500 amp hours of sealed batteries.
In addition, the OP is using a Mobicool box, which is thermoelectric cooler rather than a compressor fridge as his second fridge. They’re always on, unlike a compressor fridge which cycles on and off using a thermostat, and have a reputation for using a lot of power for not a lot of cooling.
So what? In the Ancona area, the temperature is such that the fridges will be working hard. So the battery bank needs to be large enough to cope with the load. The OP has a compressor fridge, so say 72 amp hours a day, plus the Mobicool at say 96 amp hours a day: that’s way too much for his 220 amp hour bank to sustain, even if he’s going into the marina every night and using shore power. The current batteries are knackered, not holding their charge which is why he’s seeing the battery monitor drop so quickly. Solution is to replace the batteries, add at least another 220 amp hours worth of batteries to the bank OR stop using the Mobicool box ( but still replace the batteries).

Thanks for your reply. The battery drain is quite substantial I know but contrary to your assumption the Mobicool is a compressor fridge and is quite efficient and oh the drinks are so cool so quickly.
I've load tested the batteries and yes they are working to 50% capacity so they will be given the deep six (not literally but disposed of in an environmentally friendly way. If you look in a reply to another reply (if you get my drift) I outlined the need for more batteries, the need for more solar AND just how wonderful the Mobicool 40 is. As I write this the current is stable and the voltage is high. The only thing low is the Mobicool at minus yes MINUS four!

The only reason I started this thread was that I was taken aback by the speed at which the batteries lost there charge. I thought it was more than merely duff batteries.

 

[pvb]

The battery drain is quite substantial I know but contrary to your assumption the Mobicool is a compressor fridge and is quite efficient and oh the drinks are so cool so quickly.

Which Mobicool 40 do you have?